Aerobic Energy System

Introduction

• The aerobic energy system is used when working sub-maximally (below maximum effort).
• Utilized based on the intensity and duration of the activity.

Process Overview

• Begins similarly to the lactic acid system with glycolysis.
• Glucose molecule breaks down, resynthesizing 2 ATP molecules.
• Produces 2 pyruvic acid molecules.
• Unlike anaerobic process, pyruvic acid does not convert to lactic acid.
• Can also break down fats (triglycerides) and proteins (amino acids) aerobically.

Aerobic Glycolysis

• Breakdown of carbohydrates, fats, and proteins.
• Produces pyruvic acid (no lactic acid formation due to aerobic nature).
• Occurs in the sarcoplasm of the muscle cell with the enzyme PFK accelerating the process.

Krebs Cycle

• Pyruvic acid converts to Acetyl-CoA and enters the Krebs cycle in the mitochondria’s matrix.
• Breakdown releases energy resynthesizing 2 ATP, carbon dioxide, and hydrogen ions (H+).

Electron Transport Chain

• Hydrogen ions enter the cristae of the mitochondria.
• Generates energy to resynthesize 34 more ATP and produces water (H2O).

Total ATP Production

• Aerobic system produces 38 ATP from one glucose, fat, or protein molecule.
• Process is time-consuming, suitable for lower intensity and longer duration activities.

Additional Details

• Oxaloacetic acid combines with Acetyl-CoA in the Krebs cycle.
• The electron transport chain (or transfer chain) occurs in the cristae of mitochondria.
• Beta oxidation: breakdown of fats to produce ATP.
• Capable of using multiple fuel sources.

Exam Tips

• When writing about the aerobic system, include structured points about:
  • Aerobic glycolysis
  • Krebs cycle
  • Electron transport chain
  • Use of different fuel sources (glucose, fats, proteins)
  • Mention of mitochondrial processes and ATP production

Conclusion

• The aerobic energy system is complex and suitable for activities requiring sustained energy over long periods.
• Essential to understand for exam questions due to its comprehensive nature and potential for high marks.